1. Field of the Invention
The present invention relates to concrete slab and steel construction and is directed particularly to improved apparatus and techniques for providing such construction.
2. Description of the Prior Art
The improved apparatus and techniques of the present invention pertain specifically to an improvement in providing concrete slab and steel joist construction disclosed in the present inventor's copending U. S. Patent Applications, Ser. Nos. 865,632, filed 12/29/77 and now abandoned, 491,696; and 930,950 filed 8/4/78 and now U.S. Pat. No. 4,189,883 and to U. S. Pat. Nos. 3,392,499; 3,457,818; 3,527,007; 3,624,980; 3,683,580; 3,728,835; and 4,056,908.
In the prior art techniques now commonly used for providing concrete slab and steel construction, there often occurs leakage of the concrete from the openings and joints of the pans employed to retain the poured concrete, this leading to possible faulty or less desirable concrete slabs, waste of concrete, the necessity for expending labor, money, and time to clean the spilled concrete, and other disadvantages. The present invention overcomes, or at least substantially alleviates this problem of leakage and the attendant disadvantages.
In a prior art technique used for providing poured concrete slabs, composite joists 20 (FIG. 1) are provided with their end portions 22 disposed on and welded to a composite beam 24, it being desirable that the concrete 25 poured to provide the slabs, haunch down onto the supporting beam 24, as shown in FIG. 1. The composite joists 20 comprise top chord angle members 26, lower chord angle members 30, and steel joist webbing 34, the top and bottom chord angle members 26, 30 are generally L-shaped, the top chord angle members 26 being inverted and having their vertical legs joined in back-to-back relation, as shown, with the steel joist webbing 34 extending therebetween. The lower chord angle members 30 have their vertical legs in back-to-back relation, with the steel joist webbing 34 located therebetween, the steel joist webbing 34 extending between the upper chord angle members 26 and the lower ones 30.
The end portions 32 of the top chord angle members 26 intersect the beam 24 and are generally c-shaped in cross-section so that each such member 26 has two horizontal legs. The lower horizontal legs 35 of the upper chord members 26 rest on and are welded to the beam 24 to provide a joist seat. Support rods 36 are welded to and extend transversely across the tops of the top chord angle members 26 of the composite joists 20.
Between each pair of laterally adjacent joists 20, at the region of their juncture with beam 24, there are disposed a pair of flange-edged pans 40 that have their flanged ends 42 resting on the pan support rods 36 and have their other opposite ends resting on the interior surfaces of the lower horizontal legs 35 of the upper chord members 26 and on the beam 24, so that pans 40 slope downwardly and inwardly toward the beam 24. The side edges of the pans 40 are inserted between the upper and lower horizontal legs 44 and 35, respectively of the upper chord members 26, but the pans 40 do not extend laterally over the joists 20.
Beyond the area of intersection of the composite joists 20 and the pan 40 there are corrugated metal sheets 50 that are located over the composite joists 20, the corrugated sheets 50 overlapping the flanged ends 42 of pans 40. The steel joist webbing 34 comprises upper apex portions 52 that protrude through and above the upper chord members 26 of the joist 20 and through the corrugated sheet metal framework 50 so as to anchor the poured concrete, there being pins 54 inserted between the pan 40 and the webbing apices 52.
Because the pans 40 are individually handled, there are a number of drawbacks that are described below. Also, because the pans 40 do not extend laterally beyond the upper chord members 26 and because the corrugated metal sheets 50 generally can be positioned only so that they extend only up to or slightly short of the pan support rods 36 and the bend 56 at the flange ends 42 of the pans 40, poured concrete can leak through the space between the upper chord members 26 and the pans 40, leading to the above described disadvantages.
Because the prior art fitted the individual sheet metal pans 40 between the ends of the joists 20 to allow the concrete to haunch down onto the supporting beam 24, it was necessary to expend considerable time and money in the field, this because each such pan 40 covered only the space between two adjacent joists and had to be individually handled and fitted into place and secured to the support rods 36.